558 Heritable Spiral Torsions. 



inflorescences at the top. In this respect also, my results 

 confirm those of Delpino. 



External conditions exert a great influence on these 

 secondary anomalies just as they do on the main torsions. 

 The more favorable the conditions, the rarer are the in- 

 dividuals, all of whose branches and leaves are normal. 

 Obviously this fact suggests that the factor for the iiial- 

 foruiation must be present iu all of them. 



Brief mention should also be made of the so-called 

 local torsions. They occur occasionally in all twisted 

 races. Fig. 132 represents an instance of them in Wile- 

 riana ojficinaHs. It flowered in the same year and on the 

 same l)ed as the completely twisted stem shown in Fig. 

 122 (p. 528). 



In Dipsacus laciniatus the malformation was confined 

 to these, and in Dipsacus sylvestris torsus I observed 

 them, under very special conditions of culture, on erect 

 and otherwise dectissate stems ; but on the lateral branches 

 of twisted individuals, especially on the strongest ones, 

 such as those which arise from the axils of the radical 

 leaves or from the middle of the twisted stems, they are 

 always seen to be most profusely produced. 



As in the case of fasciations, forms intermediate be- 

 tween these local torsions and the normal arran element 

 of the leaves, are relatively rare. This is not true, how- 

 ever, if the ternary whorls, split leaves, and the local 

 toi-sions on the lateral branches are included, but onlv if 

 we confinp our attention to the torsions on the main 

 stems. Unfortunately the exact measurement of tlie 

 part bearing leaves in a spiral is a matter of considerable 

 difficult}' : inasmuch as the s]:)iral begins inside the ro- 

 sette at a time when the oldest leaves have alreadv rotted 

 off and disappeared. Nevertheless I have recorded tlie l)e- 



